// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.firebase.firestore.local;

import com.google.firebase.firestore.model.ResourcePath;
import java.util.List;

/**
 * Represents a set of indexes that are used to execute queries efficiently.
 *
 * <p>Currently the only index is a [collection id] => [parent path] index, used to execute
 * Collection Group queries.
 */
public interface IndexManager {
  /**
   * Creates an index entry mapping the collectionId (last segment of the path) to the parent path
   * (either the containing document location or the empty path for root-level collections). Index
   * entries can be retrieved via getCollectionParents().
   *
   * <p>NOTE: Currently we don't remove index entries. If this ends up being an issue we can devise
   * some sort of GC strategy.
   */
  void addToCollectionParentIndex(ResourcePath collectionPath);

  /**
   * Retrieves all parent locations containing the given collectionId, as a set of paths (each path
   * being either a document location or the empty path for a root-level collection).
   */
  List<ResourcePath> getCollectionParents(String collectionId);
}
